Brain & Meninges I Flashcards
Define Scalp
Soft tissue that covers the calvaria of the skull
Anterior boundary of scalp
superciliary arches
Posterior boundary of scalp
external occidental protuberance
Lateral boundary of scalp
zygomatic arch & external auditory meatus
Layers of SCALP from outside to inside
Skin Connective tissue Aponeurosis/Galea Aponeurotica Loose CT Periosteum
Properties of skin of the scalp
- Thick and hairy
- Contains: hair follicles, sweat glands, sebaceous glands, significant arterial supply, venous drainage, lymaphatic drainage.
- Firmly attached to aponeurotic layer via dense CT
Skin of the scalp is firmly attached to _________ via _________.
aponeurotic layer, dense CT
Properties of dense CT of the scalp
- Fibro-fatty layer
- Contains nerves
- Blood vessels tightly attached to dense fibrous tissue
- Firmly attached to overlying skin and underlying aponeurotic layer
Would on the scalp bleed profusely due to:
Lack of vasospasm
How is bleeding stopped in the dense CT of the scalp?
By applying pressure against the bone
Properties of Aponeurotic layer
- Though layer of dense fibrous tissue
- Must be stitched if cut bc anchoring of superficial layers is lost
- Fans out and blends into frontalis and occipitalis
- Potential sub-aponeurotic space: scalp bleeds will pool underneath the aponeurotic layer into the loose areolar layer
Which layer of the scalp must be stitched if cut?
Aponeurotic layer
Properties of loose CT of the scalp
- Allows movement of the first 3 layers over the pericranium
- Extends beneath the orbicularis oculi into the eyelids
- Relatively avascular except for emissary veins
- Danger area of the scalp!
Why is the loose CT of the scalp the danger area?
-Blood and pus can pool here
Emissary veins connect superficial scalp veins to diploic veins of skull and intercranial venous sinuses
Bleeding in loose CT can cause:
- Generalized swelling of the scalp
- Periocular ecchymosis (aka Raccoon Eyes)
- Battle’s sign
What is Battle’s sign?
- aka mastoid ecchymosis
- Caused by nasal skull injuries
- Occurs 203 days after injury
- Extravastation of bleed underneath the aponeurotic layer, usually along the path of the posterior auricular artery
Properties of pericranium of the scalp:
- Periosteum of the skull
- Thin fibrous membrane that covers all outer bone surfaces (except joints)
- Firmly attached to sutures
- loosely attached to bone
Scalp blood supply:
- External carotid artery
- Internal carotid artery
What are the branches of the ECA in scalp?
-superficial temporal
-posterior auricular
occipital
What are the branches of the ICA in scalp?
-supertrochlear
supraorbital
Where do you find the majority of the arterial supply of the skull?
Dense CT layer of the scalp, above the aponeurotic layer
Sensory innervation of the scalp
- Trigeminal nerve (CN V)
- Occipital nerves
what are the cranial meninges?
- Outer covering of the brain
- Membranes that envelop the brain and spinal cord
What are the fxns of the membranes that envelop the brain and spinal cord?
- protect the CNV
- form a supporting framework for arteries, veins, and venous sinuses
- Enclose the subarachnoid space
What is important about the subarachnoid space?
It is vital for the normal fxn of the brain
The three CT layers of the cranial meninges:
Dura mater
Arachnoid mater
Pia mater
Dura mater
- though thick external fibrous layer
- innervated by CN V (trigeminal)
- very well vascularized
What are the layers of the Dura mater
Periosteal and meningeal
Arachnoid mater
- Think, avascular membrane
- filled with a “web” of collages (shock absorber)
- Only in longitudinal fissure
- contains cerebrospinal fluid in the subarachnoid space
Pia mater
- Thin, delicate membrane
- Highly vascularized
- Lines all fissures and sulci of the brain
- Tightly adherent ot brain surface and cranial nerve roots
Location for all intercerebral hemorrhages
Pia Mater
Largest dural infolding
Falx cerebri
Second largest dural infolding
Tentorium cerebelli
What cseparates occipital lobes from the cerebellum?
Tentorium cerebelli
Smallest dural inforlding
Diaphragma Sellae
Waht forms the roof over hypophysiial fossa?
Diaphragma Sellae
Meningitis is:
Inflammation of the meninges
What is meningitis caused by?
Bacteria (more serious) or virus (benign)
Leptomeninges
Pia + arachnoid mater
